Most people by age 50 develop some degree of arthritis. Usually, this takes the form of degenerative joint disease, or osteoarthritis that eventually afflicts nearly everyone by the time they are 65 years old. Another form of arthritis, rheumatoid arthritis, affects approximately 1% of the population with a prevalence that approaches 2% of males and 5% of females by age 65. When lupus, gout, infectious processes, metabolic processes, toxins, cancers, and the more than 100 other types of arthritis are added to these numbers, nearly everyone, if they live long enough, will suffer joint pain and arthritis. The ultimate prevalence of joint diseases is further increased by fractures, athletic injuries, neuromuscular disorders, and congenital deformities.
Common to all of the various forms of joint diseases is the presence of inflammation. All forms of inflammation, from any cause, are characterized by five cardinal signs or manifestations comprising redness, swelling, heat, pain, and the loss of function of the involved tissue. The presence of inflammation in the involved joint or tissue indicates the presence of injury or disease, while the amount of inflammation in the injured, deformed, or arthritic joint or tissue is directly proportional to the amount of damage or disease in that joint and is inversely proportional to the degree of healing in the same joint. Accordingly, the physician or surgeon treating such musculoskeletal problems is constantly trying to detect any inflammation, and, if present, to assess the degree of this inflammation in order to determine whether disease or injury is occurring, how much disease or damage is present, and whether the problem is progressing or healing.
Various methods and equipment have been developed for assessing the presence or absence of inflammation in joints and other tissues. Such methods and equipment include performing a physical examination of the involved tissue; blood tests, such as erythrocyte sedimentation rate or C-reactive protein level; radiographic tests; such as plain X-rays or magnetic resonance imaging (MRI); and research procedures, such as thermography.
In performing a physical examination, the physician begins the method of assessing the presence or absence of inflammation by asking such questions as which joints or tissue areas are causing pain, how much pain is present and how often is the pain present. The physician will then perform a physical examination to determine if there is any redness, warmth, swelling, or stiffness in these areas, and to see if the patient is experiencing any limitation or loss of function. This method of questioning and physical examination of the patient, however, does not reliably establish the presence of inflammation. For example redness over an area of pain could he a result of an overlying skin rash rather than inflammation or stiffness may be a result of a nearby muscle spasm as opposed to inflammation. Further, this method results in an assessment that is only crudely and inconsistently quantifiable. For example, the physician might ask, “If zero equals no pain and your pain level was a 10 out of 10 when you were first treated, at what level is your pain currently?” Such clinometric scales are generally inconsistent and results will vary depending, among other factors, on the manner in which the questions were asked, the physician asking the questions and the day and time the patient was questioned. Accordingly, such assessments are highly subjective and ultimately have no definite correlation with the actual degree of inflammation.
In addition to determining the presence of inflammation, the physical examination may also provides some indication of the presence and degree of inflammation. The physician or surgeon, for example, may gently squeeze or palpate the involved joint or tissue to detect swelling, warmth, or tenderness. Even if the physician detects some amount of joint or tissue swelling by palpation, there is no precise and reproducible way of determining whether the swelling represents newly inflamed tissue or just residual thickened and scarred tissue from previous, now quiescent inflammation. Detection of skin warmth is useful but cannot be quantified by simple palpation. The determination of tenderness is also useful but it only inconsistently correlates with actual inflammation. For example, the joint or tissue could be tender secondary to conditions that are not related to inflammation, such as poor circulation, diabetic-related or other causes of local nerve damage, foreign bodies, and other causes. The degree of tenderness is often assessed using a clinometric scale and has the same drawbacks as previous mentioned. The range of motion of a joint or muscle represents that tissue's functional state. Typically, the method of measuring the range of motion of a joint or muscle involves holding a plastic protractor next to the joint while the patient tries to move the joint or muscle in question. Unfortunately, problems of accuracy and reproducibility arise due to placement and stability of the protractor. It has been found that results of testing will vary even between tests performed by the same examiner on the same patient.
The method of performing blood tests to assess the presence and degree of inflammation typically involves testing of erythrocyte sedimentation rate or C-reactive protein levels. Unfortunately, such tests are nonspecific and indicate changes taking place throughout the patient's body rather than to inflammatory changes taking place in localized areas, such as a knee or finger. Further, the results of the blood tests are uniformly subject to a wide variety of physical conditions and ailments that are not related to inflammation. For example, the blood count in a patient having significant arthritis or other forms of inflammatory disease may show elevations of the white blood cells or of other blood cells called “platelets.” However, the White cell count can be elevated due to many conditions such as leukemia, allergies, drug reactions, and numerous illnesses that have little or no relationship with inflammation. Similarly, the platelet count may be increased by noninflammatory conditions such as an iron deficiency or cancer. In addition, in many inflammatory conditions such as rheumatoid arthritis, such cell counts typically show no elevation.
In the performance of another type of blood test commonly employed to detect inflammation, the erythrocyte sedimentation rate (ESR), the patient's anticoagulated blood sample is placed in a vertical glass or plastic capillary tube. After sitting for one hour, the height of the column of red blood cells that have settled to the bottom of the tube is measured. In general, the taller the column of red cells, the more inflammation exists in the patient's body. Unfortunately, this method has numerous problems. Similarly to the white blood cell and platelet tests mentioned above, the ESR may not show any elevation, eaten in the presence of clearly clinically detectable inflammation. This lack of elevation, or in some cases elevated levels not caused by inflammation, may be due to various conditions including anemia, sickled blood cells, bone marrow cancers, and diabetic kidney disease. Further, as with blood count tests, such methods only indicate the possibility of inflammation and reflect a systemic rather than a local situation.
Another blood test used in detecting inflammation involves the measurement of a patient's C-reactive protein level (CRP). Like the other blood tests used for detecting inflammation, CRP suffers from the lack of sensitivity, lack of specificity and numerous confounding factors.
As a result of the numerous difficulties associated with the various methods of assessing inflammation using blood tests and since these methods do not include measurement of the five above-mentioned markers of inflammation, such methods are indirect at best and only useful in obtaining adjuncts for detecting and quantifying inflammation.
Methods for detecting inflammation using plain radiographs, such as plain X-rays, have proved to be inadequate It has been found that if a patient has swelling capable of being shown in a X-ray, the swelling level would also be clinically evident on physical examination thereby rendering a X-ray unnecessary. In addition, any shadowy outline of a soft tissue bulge around a bone or joint indicating possible inflammation would be extremely nonspecific and may be produced by conditions that are unrelated to inflammation, such as obesity.
Methods using computerized tomography (CT) scans and magnetic resonance imaging (MRI) scans are performed occasionally to observe swelling in various tissues. Such methods, however, are relatively expensive, may be insensitive to very mild degrees of inflammation, and generally do not detect forms of inflammation that involve only minimal or no swelling. Additionally, the CT scan uses ionizing radiation. Further, an MRI cannot be used for individuals having pacemakers or metallic implants located near the subject area. Another problem with using CT and MRI scans is the difficulty of interpreting the results of the scans making them unsuitable for routine outpatient testing in a typical medical office or clinic.
Methods of detecting inflammation using thermography or infrared photography have been used to try to detect inflammation. Unfortunately, however, thermography is relatively insensitive to mild degrees of inflammation, it cannot detect any of the signs of inflammation except warmth, it is difficult to reproduce due to changes in regional blood flow, for example caused by emotional states, and it is relatively expensive and technically difficult, requiring the patient to be unclothed and placed in a climate-controlled room where ambient temperature and humidity are assiduously constant and stabilized.
Accordingly, a need exists for a relatively inexpensive, reliable, reproducible, easy to use or perform, noninvasive method and apparatus for the detection and quantification of joint and tissue inflammation that may be used in medical offices, clinics, sports and training facilities, and the like.